The present invention relates to the bonding of diamonds to suitable substrates, and more particularly, to the treatment of the diamonds to metallurgically bond the diamonds to the substrate.
This invention relates to a process for growing a metastable crystal layer over diamonds, silicon carbide, or cubic boron nitride by chemical plasma deposition under subatmospheric pressure and relatively low temperature. This can produce a metallurgical bond when mixed with suitable metal powder at its liquid or eutectic temperature and high pressure. It is also possible to produce a metallurgical bond in an aqueous solution having a heterogeneous catalyst, if used with square wave pulse current.
Several processes are disclosed in the patents and literature mentioned in the references but all use the growth of diamonds with the object of producing synthetic diamonds, departing from a diamond seed. Obviously, the principal disadvantage of all of these processes is in terms of economical considerations, at least until now.
Hibshman, U.S. Pat. No. 3,371,996, Angus et al, U.S. Pat. No. 3,661,526, and Vickery, U.S. Pat. No. 3,714,334, disclose processes for growing diamonds by facilitating or catalyzing a reaction between hydrogen and a hydrocarbon to form crystal carbon. Hibshman discloses a catalytic diamond growth process in which a solid, particulate catalytic metal is mixed with finely divided diamond seed and contacted with CO gas at a pressure of 1 atm--2000 atm and temperature of 600.degree. C. to 1100.degree. C.
Angus et al deposits a layer of a catalytic metal on the diamond seed surface and passes methane gas over the diamond at pressures of 10.sup.-8 -759 Torr and temperatures of 800.degree. to 700.degree. C. The catalyst acts as a catalytic mobile transfer medium which aids in promoting the transition of carbon in the form of a precursor in the vapor phase to the metastable diamond in the solid phase. Angus further states that the catalytic mobile transfer medium may contain materials, such as nickel, which will inhibit the formation of elemental carbides carbons.
Strong, U.S. Pat. No. 2,947,609, discloses a process for forming diamonds under high pressure (5000 to 115000 atm) and high temperature (1200.degree. C. to 2600.degree. C.) in the presence of a catalyst. Strong discloses that diamond forms at the interface of the catalyst alloy and carbonaceous material.
Caveney, U.S. Pat. No. 3,879,901, Vereschagin et al, U.S. Pat. No. 3,912,500, and Bakul et al, U.S. Pat. No. 4,097,274, disclose processes for producing diamond compacts. They compress diamond powder and a metallic binder under high pressure and temperature forming a diamond matrix which is filled and held together with the metallic binder.
St. Pierre et al, U.S. Pat. No. 4,220,455, Lee et al, U.S. Pat. No. 4,234,661, and Morelock, U.S. Pat. No. 2,247,304, disclose a process for forming a diamond compact by infiltrating a mass of diamonds coated with elemental non-diamond carbon with fluid silicon. The silicon reacts with non-diamond carbon to bind the diamonds together by a bonding medium of silicon carbide and elemental silicon. These patents disclose that the body may be formed on a substrate and that the liquid silicon, during infiltration, may penetrate the substrate to bond the diamond body or compact to the substrate.
These patents disclose processes for growing diamond crystals and creating diamond compacts. None disclose treating a diamond to enable the treated diamonds to bond to a suitable metal powder, or a the deposition of a metal and the treated diamond on a substrate by electrolytic or chemical plasma deposition.
One object of the invention is to provide a novel method for producing bondable diamonds, silicon carbide or cubic boron nitride.
Another object is to provide a container in which to produce such bondable diamonds.
Another object is to provide such a bondable diamond which will bond with a suitable substrate.
Another object is to provide such a bondable diamond which may be used for manufacturing cutting tools.
Another object is to provide such a bondable crystal which may be used for manufacturing a rotary cutting tool by electroplating but in the presence of a catalyst.
Other objects inherent in this invention will be better understood by reference to the description and examples.